Shaft coupling apparatuses are useful in various applications to enable transfer of force from one shaft to another shaft. Shaft coupling apparatuses have a variety of uses such as, but not limited to, providing force from a single input shaft to multiple driven shafts that can be used for separate operations, translating input force into a different output force (e.g., converting linear movement to rotational movement and vice versa), damping input force from one shaft using another shaft that is connected to the input shaft through the shaft coupling apparatus and that is also connected to a damping mechanism, and the like.
Rotary fluid dampers find wide-ranging use to damp input force as described above. The rotary fluid dampers generally include a damping shaft with a rotating member mounted thereon. The rotating member is disposed in a chamber that includes damping fluid, and the damping fluid provides resistance to movement of the rotating member therethrough. The damping shaft is coupled to an input shaft through a shaft coupling apparatus, and rotational movement of the input shaft is damped as a result of the damping resistance experienced by the rotating member that is mounted on the damping shaft. The rotary fluid dampers are useful in various applications where uncontrolled rotation of the input shaft is undesired, or where excessive rotation of the input shaft could cause an undesired outcome. As one example, since the onset of space exploration and satellite usage, there has been a need to control deployments of spacecraft-mounted appendages such as antennas, solar arrays, and booms. Controlling such deployments can reduce the loads of appendage spacecraft primary structures as well as momentum compensation demands on the spacecraft attitude control system. Rotary fluid dampers are useful in controlling the deployments.
Generally, the appendage deployments are controlled by passive rotary dampers. These rotary dampers normally are attached to a spring-loaded device or motor in a parallel fashion. The rotary dampers provide velocity damping to the system by either restricting fluid flow across an orifice or by electro-magnetically removing energy from the system by generating eddy currents internal to the spring-loaded device. However, such rotary dampers have a propensity to leak viscous fluid from shaft seals in a shaft coupling apparatus thereof and have inconsistent performance due to various factors, including a lack of thermal compensation.
A variety of sealing mechanisms have been developed to reduce fluid leakage in rotary dampers. For example, rubbing seals have been employed to seal shafts, but the rubbing seals are still prone to leakage, especially under harsh conditions such as in outer space. Flexible bellows have also been employed that seal an interface between an input shaft and an output shaft in a shaft coupling apparatus, with the input shaft and the output shaft maintained in separate environments and the interface between the shafts maintained in its own environment within the flexible bellows. However, the flexible bellows are prone to failure and have limited rotation.
While leakage of fluid from rotary dampers is a concern associated with shaft coupling apparatuses, other applications for shaft coupling apparatuses benefit from enhanced sealing within the shaft coupling apparatuses in different ways. For example, various sensitive fabrication processes and devices benefit from clean or ultraclean environments, and improved sealing between shafts in a shaft coupling mechanism is useful to prevent flow of contaminants between the shafts and to maintain a clean or ultraclean environment between an input shaft located outside of the clean or ultraclean environment and an output shaft that is located inside the clean or ultraclean environment.
Accordingly, it is desirable to provide shaft coupling apparatuses that include coupling mechanisms between shafts, with transfer of rotational energy between shafts supported, while providing robust separation of the shafts in their own environments to hinder leakage of fluid and/or contaminants between the environments. In addition, it is desirable to provide rotary fluid dampers and deployable devices including the shaft coupling apparatuses. Furthermore, other desirable features and characteristics of the present invention will become apparent from the subsequent detailed description of the invention and the appended claims, taken in conjunction with the accompanying drawings and this background of the invention.